الجمعة، 19 أكتوبر 2012

MCQs In Nephrology


Q 1:

A 3-year-old boy develops edema, and his general pediatrician obtains laboratory results revealing hypoalbuminemia, proteinuria, and hypercholesterolemia that are consistent with nephrotic syndrome. He sends the patient to the emergency department because the boy has not voided for 12 hours. On physical examination, he has anasarca and abdominal distention. His mucous membranes are dry, and his skin turgor is decreased. He is less active than normal but arousable. His heart rate is 145 beats/min and blood pressure is 70/40 mm Hg.

Of the following, the MOST appropriate initial therapy for this child is intravenous

A. albumin
B. albumin and furosemide
C. furosemide
D. lactated Ringer solution
E. 0.9% sodium chloride solution


The Answer :

A

Explanation:


The child described in the vignette is showing obvious signs of hypovolemia, indicating the need for albumin infusion (1 mg/kg of body weight of 25% albumin) to help restore volume in the intravascular space and reduce the edema.

This may be repeated up to four times per day, as needed.

Furosemide therapy will result in loss of intravascular volume, which would exacerbate his hypovolemia.

Normal saline alone may restore some intravascular volume temporarily, but the infusion will leak out into the interstitium rapidly and worsen the edema.

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Q 2:

A mother brings in her 3-year-old daughter because of daytime urinary incontinence and abdominal pain. The mother explained that the girl was toilet trained at 2 years of age. On physical examination, growth parameters and vital signs are normal, although the girl has mild suprapubic tenderness without associated costovertebral angle tenderness or sacral dimples.

Urinalysis shows a urine specific gravity of 1.025, pH of 6.5, 2+ blood, 1+ protein, 3+ leukocyte esterase, and positive nitrite. Urine microscopy demonstrates 5 to 10 red blood cells/high-power field, 20 to 50 white blood cells/high-power field, and 3+ bacteria. Of the following, the MOST likely etiologic agent is

A. Enterococcus faecalis
B. Escherichia coli
C. Klebsiella pneumoniae
D. Proteus mirabilis
E. Staphylococcus saprophyticus

Answer :

B

Escherichia coli is the causative organism in 80% to 90% of first-time urinary tract infections (UTIs) in children.

 Other pathogens include Klebsiella pneumonia, Proteus sp, Enterococcus sp, and Staphyloccus saprophyticus.

 Pseudomonas also can be a pathogen in immunocompromised patients or those who have received repeated courses of antibiotics for recurrent infections. 

Organisms such as E coli, K pneumoniae, and Proteus sp can reduce dietary nitrate to nitrite, so a positive urine dipstick test for nitrite, as reported for the girl in the vignette, is virtually diagnostic of gram-negative bacteruria.

 Of note, the nitrite test is much less helpful in infants.

Conversion of nitrate to nitrite may take up to 4 hours. Because infants and young children have small bladder volumes and urinate frequently, there may be insufficient time for nitrites to be formed and, therefore, the nitrite test may be negative even in the presence of a UTI caused by a gram-negative organism.

Urine pH also may be useful in diagnosing UTIs. 

Urease-producing organisms (eg, Proteus mirabilis, some strains of S saprophyticus) degrade urea into ammonia, resulting in an elevated urine pH (8.0 to 8.5).

The girl described in the vignette has symptoms of a lower UTI.

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Q3 


A 4-year-old boy presents with periorbital edema. He is receiving no medications, and his family history is negative for renal disease. On physical examination, he is afebrile; his heart rate is 88 beats/min, respiratory rate is 18 breaths/min, and blood pressure is 106/62 mm Hg; and he has periorbital and pitting pretibial edema. Laboratory evaluation shows normal electrolyte values, blood urea nitrogen of 14.0 mg/dL (5.0 mmol/L), creatinine of 0.3 mg/dL (26.5 mcmol/L), and albumin of 1.6 g/dL (16.0 g/L). Urinalysis demonstrates a specific gravity of 1.020; pH of 6.5; 3+ protein; and negative blood, leukocyte esterase, and nitrite. Microscopy results are normal. Additionally, complement component (C3 and C4) values are normal, and results of serologic testing for antinuclear antibody, hepatitis B and C, and human immunodeficiency virus are negative. Of the following, you are MOST likely to advise the parents that

A. a renal biopsy is warranted to determine the optimal treatment
B. disease relapse can be expected in fewer than 25% of those achieving remission
C. patients who relapse have a similar prognosis as those who do not respond to steroids
D. remission is expected in more than 75% of patients who receive corticosteroid treatment
E. tacrolimus is the preferred treatment for patients who do not respond to corticosteroids

Answer :

D


The boy described in the vignette has signs and symptoms of nephrotic syndrome.

Causes of nephrotic syndrome can be subdivided into

A-  Primary glomerulopathies (eg, minimal change disease, focal segmental glomerulosclerosis, mesangial
      proliferative glomerulonephritis).

B- Secondary glomerulopathies (eg, lupus nephritis, membranoproliferative glomerulonephritis due to
     hepatitis C, and human immunodeficiency virus nephropathy).

The initial evaluation of new-onset nephrotic syndrome centers on establishing whether it is due to a primary glomerulopathy and warrants an empiric trial of corticosteroids.

 Clinical features that suggest secondary glomerulopathy include :

- Moderate-to-severe hypertension.
- Gross hematuria.
-  Laboratory markers suggestive of a secondary glomerulopathy include :
                   - Azotemia,
                   - Hypocomplementemia.
                   - Positive antinuclear antibody finding.
                   - Positive serologic test for human immunodeficiency virus or hepatitis B or C.


The normal blood pressure and renal function as well as the absence of hematuria, hypocomplementemia, or a positive serologic test for lupus or viral infection described for the boy in the vignette are consistent with primary glomerulopathy. Accordingly, this child should receive a 4- to 6-week trial of daily corticosteroids because nearly 90% of childhood nephrotic syndrome cases are sensitive to steroids.

Although 90% of pediatric patients achieve a state of remission with corticosteroids, 50% to 70% experience at least one relapse during their disease course.


Unless clinical or serologic findings raise the possibility of an underlying glomerulonephritis, renal biopsy is not warranted. 

The steroid response, not renal biopsy findings, is the best predictor of the prognosis for childhood nephrotic syndrome. 

Steroid-sensitive patients, even those who have a relapsing course, have a better prognosis than steroid-resistant patients.

The approximately 10% of patients who are steroid-resistant have a guarded prognosis, with a risk
of developing chronic renal failure.

Steroid-resistant patients require a renal biopsy to establish histologic information.

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Q 4:


A 4-year-old girl who has presumed minimal change nephrotic syndrome presents at your office because of a recent rapid weight gain. The mother reports that the urine protein determinations have been 4+ for 2 weeks. Physical examination reveals generalized edema, blood pressure of 115/74 mm Hg, and heart rate of 85 beats/ min. Findings on the remainder of the examination are normal. The urine protein is 4+. You prescribe oral prednisone. Two days later the mother reports that the girl's urine is dark, she has not voided for 12 hours, and she has abdominal pain.
Of the following, the most likely cause of this girl's hematuria and decreased urine output is:

A.         acute glomerulonephritis
B.         hemorrhagic cystitis
C.         pyelonephritis
D.         renal vein thrombosis
E.         tubulointerstitial nephritis due to steroid therapy


Answer :

D


The development of RVT is usually heralded by the sudden onset of gross hematuria and unilateral or bilateral flank masses. Patients can also present with microscopic hematuria, flank pain, hypertension, or oliguria. RVT is usually unilateral. Bilateral RVT results in acute kidney failure.


Renal vein thrombosis (RVT) occurs in 2 distinct clinical situations:

   -  In newborns and infants, RVT is commonly associated with asphyxia, dehydration, shock, sepsis,
            congenital hypercoagulable states, and maternal diabetes.
    -  In older children, RVT is seen in patients with nephrotic syndrome, cyanotic heart disease, inherited
               hypercoagulable states, and sepsis and following kidney transplantation and following exposure to
               angiographic contrast agents.


RVT begins in the intrarenal venous circulation and can spread to the main renal vein and inferior vena cava. Thrombus formation is mediated by endothelial cell injury resulting from hypoxia, endotoxin, or contrast media.

Other contributing factors include hypercoagulability from either nephrotic syndrome or mutations in genes that encode clotting factors (i.e., factor V Leiden deficiency); hypovolemia and diminished vascular blood flow associated with septic shock, dehydration, or nephrotic syndrome; and intravascular sludging caused by polycythemia.



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Q 5:


Urinalysis obtained during a health supervision visit of a 10-year-old boy reveals 2+ protein. The remainder of the urinalysis is normal. Results of family and personal medical histories as well as physical examination of the boy are negative.

Of the following, the BEST next step is to:



A.         arrange consultation with a nephrologist

B.         examine the urine of family members

C.         obtain a 24-hour urine sample for protein quantification

D.         obtain renal ultrasonography

E.         perform a urinalysis on the first morning void


Answer :

E




            If urinalysis reveals protein in the urine of any child, an evaluation is mandatory. The urine also should be assessed for the presence of red blood cells (RBCs), white blood cells, nitrites, and bacteria. RBCs in conjunction with protein on urinalysis suggest renal parenchymal disease or urinary tract infection. Nitrites or bacteria in a clean-catch or catheterized specimen strongly indicate urinary tract infection. Most patients who have proteinuria do not have edema due to a reduction of oncotic pressure.



            In the absence of symptoms such as edema, abdominal or flank pain, dysuria, or fever, evaluation of proteinuria can proceed in a stepwise manner. The most prudent initial step is to obtain a first-morning specimen and repeat the urinalysis. If the specimen is negative for protein, the diagnosis of orthostatic proteinuria (OP) can be made. If there is protein in the urine on a first-morning specimen, protein and creatinine in the urine should be quantitated. If the protein/creatinine (P/C) ratio is less than 0.25, observation and repeat measurement of the ratio within the next month are appropriate. A P/C greater than 0.25 on the first-morning specimen warrants further evaluation.



            OP is diagnosed in a patient who has a finding of proteinuria by dipstick on a random (mid-day) sample and a completely negative finding by dipstick on the first-morning sample. This benign condition does not portend long-term risk for subsequent renal disease. Its cause remains obscure, but it may be related to compression of the renal vein from the kidney. Regardless of the mechanism, affected patients do not require periodic evaluation. It is worth mentioning that OP cannot be the ultimate diagnosis in a patient who has RBCs in the urine.



            A false-positive result for protein in the urine may be seen in a sample that is extremely alkaline (urine pH, >8.0). Proteinuria may be masked with a very dilute urine (specific gravity, <1.005). Protein also may be transiently present in the urine of patients who have fever or acute illness. It is prudent to re-examine the urine at a later date in these patients.



            Renal ultrasonography eventually may be necessary in a patient who has proteinuria that does not disappear on the first-morning specimen. A 24-hour urine collection for protein determination also is reserved for patients who have proof of protein in the urine on the first-morning specimen. A family history always is essential in the evaluation of any patient, although there is no evidence that OP is a familial disease. The benign nature of OP obviates the need for a consultation with a nephrologist.

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Q6 :




A 12-year-old boy presents to the emergency department with a 3-day history of tea-colored urine that began 2 days following an upper respiratory tract infection. There is no history of dysuria, and findings on physical examination are normal. The family history is negative for any kidney disease. His blood pressure is 115/70 mm Hg. Urinalysis reveals: specific gravity, 1.025; pH, 6.0; red blood cells, too numerous to count; 1+ protein; and 0 to 2 white blood cells. Electrolyte levels are normal.

Of the following, the MOST likely diagnosis is:



A.         Alport syndrome

B.         focal segmental glomerulosclerosis

C.         hypercalciuria

D.         immunoglobulin A nephropathy

E.         postinfectious glomerulonephritis

Answer :


D




Immunoglobulin A nephropathy (IgAN), or Berger diseas. 

The most common presenting symptom is gross hematuria following an upper respiratory tract infection. There is generally no pain associated with the gross hematuria, although some patients report “loin” pain.

 Any child who has gross hematuria, defined as pink, red, or brown-colored urine, must be evaluated. The first step is to analyze the urine for the presence of red blood cells (RBCs).

 The absence of RBCs in urine that is discolored indicates the presence of hemoglobin, myoglobin, or porphyrins. If RBCs are present, as in the patient described in the vignette, IgAN must be considered in the differential diagnosis.

Urinalysis in any child who has gross hematuria also should assess the presence of protein (indicating renal parenchymal disease), white blood cells (suggesting either renal parenchymal disease or infection), and nitrites (suggesting urinary tract infection).

 It is important to note that nephrolithiasis and urolithiasis are extremely uncommon in the absence of abdominal or urethral pain. Serum electrolyte levels must be evaluated to assess renal function. Finally, renal ultrasonography should be performed to ascertain the presence of a structural malformation such as cystic disease, hydronephrosis, tumor, or obstruction.

Alport syndrome, or familial nephritis, is a kidney disease caused by abnormal collagen deposition in the basement membrane of the glomerulus. This slowly progressive disease generally affects males. Alport syndrome may present with either gross or microscopic hematuria, but it is much less common than IgAN. Associated features include deafness and ocular abnormalities. 

Focal segmental glomerulosclerosis is a glomerular disease that typically presents with proteinuria. Hematuria may be present, but it is not the predominant feature. 

Hypercalciuria typically presents with hematuria, but the hematuria is usually microscopic, unless accompanied by lithiasis. Lithiasis almost always is associated with excruciating flank, abdominal, or urethral pain. 

Finally, postinfectious glomerulonephritis usually presents with gross hematuria, but generally at least 2 weeks after an upper respiratory tract infection and often is associated with a sore throat.


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Q 7 :



You are evaluating a 2-month-old infant for microscopic hematuria. He has a history of respiratory distress syndrome and bronchopulmonary dysplasia and currently is receiving caffeine and furosemide. Urinalysis reveals: specific gravity, 1.010; pH, 6.5; 15 to 20 red blood cells; no protein; and 0 to 2 white blood cells. Electrolyte levels are normal.

Of the following, the MOST likely cause of the hematuria is:



A.  benign familial hematuria

B.  hypercalciuria

C.  multicystic kidney dysplasia

D.  tumor

E.  urinary tract infection

Answer :

B



Furosemide therapy has been associated with the development of hypercalciuria, most commonly among infants who receive the drug for treatment of bronchopulmonary dysplasia. The first sign of hypercalciuria is usually microscopic hematuria with red blood cells (RBCs) in the urine. Hypercalciuria usually is asymptomatic, but occasionally may be severe enough to result in calcium stone formation and abdominal pain. Any patient who is receiving chronic furosemide or loop diuretic therapy, such as the infant described in the vignette, should be screened routinely for RBCs in the urine.

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Q 8:

An 11-year-old girl who has chronic renal failure of unknown cause is found to have a hemoglobin of 6.5 g/dL (65 g/L) on an incidental blood count. She does not report increasing fatigue. She is being maintained on chronic ambulatory peritoneal dialysis. Results of other laboratory studies include: reticulocyte count, 0.3% (3 x 10-3); white blood cell count, 7,900/cu mm (7.9 x 109/L); platelet count, 399 x 103/cu mm (399 x 109/L); mean corpuscular volume, 84 fL; and creatinine, 2.5 mg/L (221 mcmol/dL).
Of the following, the MOST appropriate therapy for this girl's anemia is:

A. ferrous sulfate orally
B. ferrous sulfate parenterally
C. multivitamins that include copper
D. recombinant erythropoietin subcutaneously
E. red blood cell transfusion

Answer :

D




 Erythropoietin is a glycoprotein synthesized predominantly in the kidney. Its production is induced by hypoxia, and its primary effect is to stimulate erythroid progenitor cell proliferation.

 Administration of rhEPO parenterally three times a week allows most patients on dialysis to become transfusion-independent. Dosages have varied, but many centers start dialysis-dependent patients at 50 to 100 U/kg of body weight subcutaneously or intravenously three times a week. Subcutaneous administration may be more efficacious. 

            The primary side effects of rhEPO in chronic renal failure are the development of iron deficiency (related to increased iron utilization), hypertension, and seizures.

 The administration of iron helps to prevent iron deficiency. The hypertension probably is due to reversal of the vasodilatory effects of the anemia and occurs in only a minority of patients. The etiology of the seizures is not clear and may not differ from that seen in patients who have chronic renal failure and are not receiving rhEPO.

   
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Q 9



Of the following, the MOST accurate statement regarding ureteroceles is that they:

A.   are classically diagnosed by computed tomography
B.   are more common in males than in females
C.   are the most common cause of urinary retention in females
D.   rarely are associated with duplicated ureters
E.    usually do not present with a urinary tract infection


Answer


C


 

Ureteroceles are cystic dilatations of the distal submucosal or intravesical portion of a ureter. They are seen in about 1% to 2% of children who undergo cystoscopy, although the incidence in the general pediatric population is unknown. Ureteroceles frequently are associated with duplicated ureters (two ureters intersecting with the kidney). They may be located entirely within (intravesical) or outside the bladder (ectopic), at the bladder neck or urethra. The etiology of ureteroceles remains elusive. The current theory suggests that they derive from an intrinsic defect in the ureteral bud and from abnormal incorporation of the ureteral bud into the urethra and bladder.


            Various anomalies are associated with ureteroceles, including duplicated ureters. Because of the potential association with duplicated ureters, renal ultrasonography should be undertaken in affected children to assess for hydronephrosis. In addition, contralateral vesicoureteral reflux or obstruction may occur. Finally, about 10% of ureteroceles may be bilateral.



            Ureteroceles are the most common cause of urinary retention in females. They usually manifest in early childhood with symptoms suggesting infection of the urinary tract: fever, dysuria, foul-smelling urine, hematuria, and abdominal pain. If the ureterocele is located near or in the urethra, prolapse into the urethra may occur, resulting in urinary retention.


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Q 10



A 5-year-old girl visited her doctor 2 weeks ago to treat a sore throat. He prescribed an antibiotic that she took, but the parents cannot recall its name. She presents at the emergency department today with gross hematuria and periorbital edema. She has a blood pressure of 150/95 mm Hg. The attending physician suspects she has acute postinfectious glomerulonephritis (PIAGN). Urinalysis reveals too numerous-to-count red blood cells and 2+ protein. To confirm the diagnosis, you measure serum complement levels; the C3 is 57 mg/dL (5.7 g/L) (low) and the C4 is 24 mg/dL (2.4 g/L) (normal). Within 3 days, the gross hematuria and hypertension resolve spontaneously. Six weeks later you see her in your office.

Of the following, the laboratory results that would be consistent with resolving PIAGN are:





        C3           Hematuria          Protein

A.     Low        Microscopic      Negative         
B.     Low        Microscopic      Positive           
C.     Normal   Microscopic      Negative         
D.     Normal   Microscopic      Positive           
 
E.     Low        None                Negative   



Answer


C

      Acute postinfectious glomerulonephritis (PIAGN) is the current term used to describe any acute inflammation of the kidney caused by an infectious agent that results in gross hematuria, edema, and hypertension. Historically, the most common pathogen causing PIAGN was group A beta-hemolytic Streptococcus. It is the most common cause of PIAGN in children. Other infectious agents include Staphylococcus aureus, S epidermidis, echovirus, human immunodeficiency virus, adenovirus, influenza A virus, and Epstein-Barr virus.

            PIAGN can occur in children of any age, but most typically affects those younger than 12 years. Pharyngitis and pyoderma are the most likely antecedent infections associated with PIAGN. Throat infection usually precedes the onset of hematuria, edema, and hypertension by about 2 weeks; pyoderma may precede the renal manifestations by as many as 6 weeks.

            Because the symptoms of PIAGN may mimic any acute glomerulonephritis, it is essential to obtain appropriate laboratory tests to confirm the diagnosis. Urinalysis typically reveals red blood cells and red blood cell casts. Serum electrolyte concentrations are generally normal in PIAGN, although some patients may experience a decline in renal function. Those who have elevated serum creatinine levels should have the creatinine measurement repeated. In patients in whom the creatinine levels continue to rise after several days, one must entertain the possibility that the patient may have rapidly progressive glomerulonephritis, requiring immediate consultation with a nephrologist.

            Because the complement system is involved in the pathogenesis of PIAGN, serum complement 3 (C3) levels are reduced. Low C3 and C4 levels must raise the suspicion of other causes of AGN, such as membranoproliferative GN or lupus nephritis. One additional test that can be performed is evaluation of anti-DNAse B, which is almost uniformly abnormal in PIAGN.

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Q 11


You are seeing an 11-year-old girl who had a previous history of urinary tract infection at age 2. Previous radiographic studies have included renal ultrasonography and voiding cystourethrography, both of which yielded normal results. She has no complaints at this time. Urinalysis reveals 1+ nitrites, but is otherwise negative. Results of a urine culture from a clean catch specimen reveal greater than 100,000 cfu/mL Escherichia coli.

Of the following, the MOST appropriate treatment for this patient is:



A. intramuscular ceftriaxone
B. observation
C. oral ciprofloxacin
D. oral nitrofurantoin
E.  oral trimethoprim-sulfamethoxazole

Answer

B

Several prospective studies have shown that there is no value to identifying or treating asymptomatic children who have bacteriuria, such as the girl in the vignette. Unnecessary treatment only leads to the emergence of resistant strains of bacteria; many patients clear the bacteriuria uneventfully

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Q 12


A 12-year-old boy presents to the emergency department with a 3-day history of tea-colored urine that began 2 days following an upper respiratory tract infection. There is no history of dysuria, and findings on physical examination are normal. The family history is negative for any kidney disease. His blood pressure is 115/70 mm Hg. Urinalysis reveals: specific gravity, 1.025; pH, 6.0; red blood cells, too numerous to count; 1+ protein; and 0 to 2 white blood cells. Electrolyte levels are normal.
Of the following, the MOST likely diagnosis is:

A. Alport syndrome
B. focal segmental glomerulosclerosis
C. hypercalciuria
D. immunoglobulin A nephropathy
E.  postinfectious glomerulonephritis

Answer

D

Immunoglobulin A nephropathy (IgAN), or Berger disease, is a glomerular disease that occurs most often during the second decade of life and in adults. The most common presenting symptom is gross hematuria following an upper respiratory tract infection. There is generally no pain associated with the gross hematuria, although some patients report “loin” pain. 

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Q 13


One month ago, a 10-year-old boy presented to you with edema of the face, hands, and feet. Urinalysis revealed 20 to 25 red blood cells and 4+ protein. You diagnosed nephrotic syndrome and placed him on a recommended regimen of oral steroids. His face now exhibits cushingoid features, but his edema has not subsided. Urinalysis today reveals 4+ protein and moderate blood.
Of the following, the MOST likely diagnosis at this time is:

A. focal segmental glomerulosclerosis
B. Henoch-Schönlein purpura
C. immunoglobulin A nephropathy
D. minimal-change nephrotic syndrome
E. postinfectious acute glomerulonephritis


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